Singapore, 16 March 2023 – A team of researchers from the Singapore Eye Research Institute (SERI), Singapore National Eye Centre (SNEC), Singapore General Hospital (SGH) and Duke-NUS Medical School (Duke-NUS) have discovered that an existing drug that regulates lipids (fatty substances in the blood) could possibly be used to treat corneal nerve damage in patients with type 2 diabetes.
Known as fenofibrate, the drug has shown promise in corneal nerve regeneration in a clinical trial conducted among 30 patients with diabetic corneal neuropathy. The researchers hope that the encouraging results could pave the way for a new and affordable treatment option for patients with this condition.
Prevalence of Diabetic Corneal Neuropathy
The human cornea – the transparent part of the eye that covers the iris and the pupil – has the densest nerve supply in the body. Diabetic corneal neuropathy is a common complication in patients with type 2 diabetes. High blood sugar levels for a prolonged duration injures nerves throughout the body, including corneal nerves, and such corneal nerve damage affects some 47% to 64% of patients. It is often underdiagnosed as patients are usually asymptomatic. These patients may have decreased corneal sensation, corneal wounds that do not heal, corneal infections, or even complications like corneal perforation that can significantly affect their vision or lead to blindness.
Currently, treatment for diabetic corneal neuropathy only targets its symptoms. Another drug, called nerve growth factor, which treats nerve damage in the eye, is expensive, requires frequent application, and is not available locally. On the other hand, fenofibrate, a drug used to lower cholesterol, is more readily available here and was found to have potential as a therapeutic option for diabetic corneal neuropathy.
Observations from clinical trial
The results of the study led by Associate Professor Liu Yu-Chi, Clinician Scientist at SERI and SNEC were published in November 2022 in the journal Diabetes. It stated that after the 30 patients (60 eyes) received oral fenofibrate treatment for 30 days, there was significant stimulation of corneal nerve regeneration and suppressed neuroinflammation, as well as a reduction in nerve swelling. The corneal cells were also observed to become more regular in structure.
The researchers analysed that fenofibrate treatment led to changes in three areas. Firstly, the drug increases production of proteins that help in the growth and survival of neurons and prevents their damage. Secondly, its ability to lower lipids helps reduce high cholesterol, a known risk factor for neuropathy. Finally, the drug’s anti-inflammation and anti-clotting properties help improve the speed at which electrical signals move through nerves.
"This study opens a new avenue for the treatment of diabetic corneal neuropathy. We aim to improve these patients’ clinical outcomes and enhance cost-effectiveness of medical care,” said Assoc Prof Liu. While the results of the initial study have shown much promise for diabetic corneal neuropathy, Assoc Prof Liu also cautions that some patients may experience side effects like nausea, heartburn, stomach pain, constipation, diarrhoea after taking fenofibrate. The dosage also has to be adjusted by doctors based on the patient’s conditions. As such, they should only take this medicine only as directed by their doctor.1
“Treatments for cornea nerve damage due to poorly controlled diabetes are limited and do not alter the natural course of the disease. We are excited to discover a treatment that regenerates damaged corneal nerves. Furthermore, the same drug may be effective against diabetes-related nerve damage in other parts of the body,” said Dr Tan Hong Chang, Senior Consultant, Department of Endocrinology, SGH, and the study’s joint corresponding author.
“This innovative solution developed by one of our Academic Medical Centre’s clinician-scientists brings hope of an affordable and safe treatment that can save people’s eyesight, and promises to be a significant advance in our ongoing war against diabetes,” said Professor Thomas Coffman, Dean of Duke-NUS Medical School.
Larger studies underway to further ascertain effectiveness of drug
The next steps for the researchers would be to conduct large-scale randomised controlled trials, among at least 200 patients, who will be selected largely from SNEC’s clinics. The researchers will be fine-tuning the dosage and treatment duration of trial participants, based on their severity of diabetic corneal neuropathy.
Development of topical fenofibrate eye drops is ongoing for better clinical adoption
The team is also discussing with a pharmaceutical company to formulate fenofibrate into topical eye drops. The topical form will eliminate the systemic side effects of oral fenofibrate, improve patients’ compliance, and better the clinical adoption.
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